Neither Barack Obama nor Mitt Romney attended the event, so space panelists addressed two empty chairs with their ideas, paying tribute to Eastwood’s "invisible Obama" act at the Republican national convention. The delegates poked fun at the candidates but were deadly serious about space-age ideas.

The buzz really started in April, with the arrival of Planetary Resources[5] (PR) – a new venture made up of the Nasa scientists Chris Lewicki and Tom Jones and the space entrepreneurs Peter Diamandis and Eric Anderson – which hopes to mine near-earth asteroids within ten years.

PR’s timing couldn’t be better. Not since the early space missions have "interplanetary exploration", "asteroids" and all things Martian been household buzzwords. It's all thanks to Nasa’s Mars rover Curiosity, which, as I write, is unlocking the geological secrets of a pyramid-shaped rock named Jake Matijevic.

As if this wasn’t exciting enough, the world was recently given a glimpse of the treasure troves we could find orbiting in space and right here on earth.

Russia recently revealed[6] that the crater of a meteorite that landed in Siberia 35 million years ago, contains trillions of carats of rare diamonds. The Soviet government discovered the deposit in 1970s but it’s only now that documents have been disclosed revealing the true extent of the diamond hoard, which scientists say could supply the entire world for 3,000 years.

The growing interest in space mining is understandable. Based on known reserves on earth and growing consumption in developing countries, it is estimated that key elements such as gold and platinum, essential for modern industries, could be exhausted within 60 years. Yet with analysts claiming that mining in space is not economically feasible, are the scientists' ideas a little starry-eyed?

Due to Nasa’s tightening budget, just $800m is currently available to bring rock samples from Mars back to earth, not a substantial amount considering an upcoming mission to return just two ounces of material from an asteroid will cost $1bn.

As for PR, this company has the financial backing of the Google billionaires Eric Schmidt and Larry Page but how much of a profit can be made from mining platinum and gold, valued at about $1,600 an ounce, when logistical costs are so high?

The 100km Popigai meteorite crater found in Siberia is said to contain diamonds that are two times harder than regular ones but these resources can only be used for industrial use, not jewellery. Currently, the cost of mining far outweighs the asking price for industrial diamonds and profits can only be made from selling gemstone diamonds. The market already has a more easily accessible substitute for this material: lab-grown industrial diamonds.

The world, it seems, is stuck in a catch-22 situation – it needs money to fund mining and it need mining to make money. The question is, should scientists, entrepreneurs and governments wait until earth’s reserves run out or take a giant leap of faith?

Sarah Blackman is the energy features writer for the NRI Digital[7] network.